Stereolithography is a technology whereby three-dimensional objects, e.g. models, can be formed using computer guided ultraviolet light, such as that from a laser beam, to solidify superposed layers of a liquid ultraviolet-curable composition. Typically, a support is positioned beneath the surface of a reservoir containing the ultraviolet-curable composition. As each successive cross-sectional layer of the object being polymerized is formed, the liquid level is raised or the support is lowered and another layer is formed until the entire three-dimensional object is formed within the liquid reservoir. The geometry and dimensions of each cross-sectional layer are determined by a computer model which controls the positioning of the ultraviolet light.
It is not uncommon for levels of distortion, e.g., shrinkage, of objects made by stereolithography to range from about 10 to 30 percent. Typical problems which can arise from such distortion include, for example, warpage of flexible substrates, loss of adhesion, crazing of a coating, and the like. Since ultraviolet-cured objects made by stereolithography are often used as dimensionally accurate models for setting up mass production processes, the minimization of distortion is extremely important.
Additives such as acrylates and methacrylates have been proposed for use in ultraviolet-curable liquid compositions in order to reduce distortion of objects made therefrom. However, further improvements are needed. Thus, new distortion control additives for ultraviolet-curable liquid compositions are desired which can impart improved distortion control properties.